1. Field of the Invention
The present invention relates to a device which permits easy delivery of a sterile water or pharmaceutical liquid used in the fields of medical treatment, health and hygienics or sanitation, biochemistry, bacteriology, or in the fields associated with foods and drinks and cosmetics. More particularly, the present invention is concerned with such a liquid purifying device which is suitably used for dispensing solutions for soaking, cleaning or storing contact lenses.
2. Discussion of the Prior Art
Various aqueous solutions, pharmaceutical liquids or liquid drugs are used in the fields of medical treatment, health and hygienics, biochemistry and bacteriology, for example. Examples of such liquids include pharmaceutical liquids used in medical institutions such as hospitals, and soaking or cleaning solutions for contact lenses. The liquids are generally purchased as accommodated in comparatively large containers, and are dispensed in desired amounts when needed, for a relatively long period. The containers have liquid delivery outlets through which the liquids are delivered. This arrangement for delivery or dispensation of the liquids suffers from contamination of the liquids by bacteria or microorganisms which may come into the containers through the liquid delivery outlet.
In view of the above drawback, there were developed two types of liquid purifying devices as disclosed in laid-open Publication Nos. 62-125804 and 62-90706 of unexamined Japanese Patent Application and unexamined Japanese Utility Model Application, respectively. The assignee of the present application contributed to the development of these devices. These devices use a container for accommodating a liquid, and a micro-porous membrane filter disposed in a liquid delivery path through which the liquid is delivered out of the container. The container is formed of a suitable elastic material so that the container body is elastically contracted, by squeezing hand pressure, to deliver the liquid, and is elastically restored to its original shape upon releasing of the hand pressure. The micro-porous membrane filter permits the liquid to flow therethrough but inhibits passage of bacteria therethrough. In this device, the bacteria contained in the liquid are removed by the micro-porous membrane filter provided in th liquid delivery path, when the liquid is delivered or dispensed from the container. Accordingly, even the liquid which is contaminated by bacteria within the container may be purified so that the liquid as dispensed may be made sterile.
In the proposed liquid purifying devices, however, the liquid delivery path or passage for delivering the liquid from the container is held exposed to the ambient atmosphere. Therefore, the interior of the liquid delivery passage, and the micro-porous membrane filter disposed therein may be contaminated by bacteria introduced through the exposed end of the passage. In particular, the proposed liquid purifying devices suffer from the problem that the bacteria may easily enter the liquid delivery passage, together with a flow of the ambient air into the interior of the container through the liquid delivery passage, due to a comparatively reduced pressure within the container, which is developed when the contracted container is elastically restored to its original shape.
To solve the above-described problem, another liquid purifying device as disclosed in U.S. Pat. No. 4,940,542 was developed by the assignee of the present invention. This device includes a first valve for permitting a supply flow of a compressed gas or a liquefied gas therethrough into the interior space of the container, but inhibiting a discharge flow of the gas and the liquid therethrough out of the interior space. The device further includes a second valve disposed between an outlet of the liquid delivery path and a micro-porous membrane provided in the path, for selectively closing and opening the liquid delivery path. The device also includes dispensing means of a push-operated type, which is manually operated to selectively open and close the second valve.
In the proposed liquid purifying device, the compressed or liquefied gas is introduced through the first valve into the interior space of the container, and the liquid delivery path is closed by the second valve while the liquid is not delivered. This arrangement effectivcly prevents the entry of bacteria through the liquid delivery outlet toward the micro-porous membrane. Accordingly, the proposed device is capable of dispensing the liquid in a sterile condition, for a prolonged period of time, with high liquid purifying stability, as compared with the conventional device without the first and second valve. Further, the use of the push-operated dispensing means makes it considerably easy to dispense or deliver the liquid from the container through the liquid delivery path. Namely, the opening of the second valve for dispensing the liquid can be effected only by pushing down the dispensing means. While the liquid is not delivered, the second valve is automatically placed in its closed position so as to close or shut the liquid delivery path. Thus, the push-operated dispensing means is considerably easy to handle.
In the thus constructed liquid purifying device, however, where the container includes as an integral part a rubber bulb or other means for supplying the pressurized gas into the interior space of the container through the first valve, this pressurized-gas supply means may interfere with the operation of the push-operated dispensing means for opening and closing the second valve, owing to the relative positions of the supply means and the dispensing means. In this respect, it is desirable that both of the pressurized-gas supply means and the dispensing means are installed on the uppcr lid portion of the device, to assure improved ease of handling or manipulation of the two means. When the gas supply means is located near to the dispensing means in the relatively narrow lid portion, the operation of one of the two means is inevitably disturbed by the presence of the other means.